Recently I ran into issues when I was fitting a graph to a parametric function. After fitting, I was making a copy of a TF2 using TF2::GetFormula ()->GetExpFormula(“P”) [1] and then computing fit error per point (data - fit). After a while, I found out that TFormula::GetExpFormula(“P”) rounds the parameters of the functions to 6 decimal places and this was producing very weird shapes for the error distribution.

Is there a way to specify the number of decimal places to use in TFormula::GetExpFormula(“P”)? If not, the fact that 6 decimal places is always used should be clearly stated in the documentation.

I think this is an issue that we should fix. Since the parameters are double we should round them to the double precision value. I will open a GitHub issue on this